U.S. patent application number 13/454137 was filed with the patent office on 2012-11-01 for scroll compressor.
Invention is credited to Sungyong AHN, Cheolhwan KIM, Sanghun SEONG.
Application Number | 20120275946 13/454137 |
Document ID | / |
Family ID | 47068033 |
Filed Date | 2012-11-01 |
United States Patent
Application |
20120275946 |
Kind Code |
A1 |
SEONG; Sanghun ; et
al. |
November 1, 2012 |
SCROLL COMPRESSOR
Abstract
A scroll compressor is provided that may include a fixed scroll
having a fixed wrap, an orbiting scroll engaged with the fixed wrap
to define a compression chamber, a rotation shaft having a shaft
portion eccentrically located with respect to the orbiting scroll,
a pin portion located at an end of the shaft portion and having a
diameter smaller than a diameter of the shaft portion, and a
bearing located at an end of the pin portion, and a drive that
drives the rotation shaft. The pin portion may be inserted through
one of the fixed scroll or the orbiting scroll, and the orbiting
scroll may be rotatably coupled to the bearing.
Inventors: |
SEONG; Sanghun; (Seoul,
KR) ; KIM; Cheolhwan; (Seoul, KR) ; AHN;
Sungyong; (Seoul, KR) |
Family ID: |
47068033 |
Appl. No.: |
13/454137 |
Filed: |
April 24, 2012 |
Current U.S.
Class: |
418/55.1 |
Current CPC
Class: |
F01C 21/02 20130101;
F04C 29/0071 20130101; F04C 23/008 20130101; F04C 18/0253 20130101;
F04C 2240/10 20130101; F04C 18/0215 20130101 |
Class at
Publication: |
418/55.1 |
International
Class: |
F04C 18/00 20060101
F04C018/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2011 |
KR |
10-2011-0040386 |
Claims
1. A scroll compressor, comprising: a fixed scroll having a fixed
wrap; an orbiting scroll disposed on top of and engaged with the
fixed wrap to define compression chambers; an upper frame disposed
above the orbiting scroll; a rotation shaft having a shaft portion
eccentrically located with respect to the orbiting scroll, a pin
portion located at an end of the shaft portion and having a
diameter smaller than a diameter of the shaft portion, and a
bearing located at an end of the pin portion; and a drive that
drives the rotation shaft, wherein the pin portion is inserted
through the orbiting scroll, and the orbiting scroll is rotatably
coupled to the bearing.
2. The scroll compressor of claim 1, further comprising a high
pressure chamber disposed above the upper frame.
3. The scroll compressor of claim 2, wherein, during operation,
high pressure fluid within the high pressure chamber pushes the
orbiting scroll away from the upper frame, thereby reducing wear
and noise.
4. The scroll compressor of claim 2, further comprising a discharge
pipe that discharges compressed refrigerant from the high pressure
chamber.
5. The scroll compressor of claim 1, wherein the upper frame
divides an inner area of the scroll compressor into a high pressure
chamber and a low pressure chamber.
6. The scroll compressor of claim 5, wherein the high pressure
chamber is disposed above the upper frame and the low pressure
chamber is disposed below the upper frame.
7. The scroll compressor of claim 1, wherein the pin portion and
the shaft portion are integrally formed with each other.
8. The scroll compressor of claim 7, wherein the pin portion is
inserted into the bearing and fixed thereto.
9. The scroll compressor of claim 8, wherein the pin portion has a
section in the form of a polygonal or non-circular shape.
10. The scroll compressor of claim 1, wherein the pin portion is
coaxially disposed with respect to the shaft portion, and the
bearing is eccentrically disposed with respect to the pin
portion.
11. The scroll compressor of claim 1, wherein the pin portion and
the bearing are integrally formed with each other.
12. The scroll compressor of claim 11, wherein the pin portion is
inserted into the shaft portion and fixed thereto so as to be
rotatable together with the shaft portion.
13. The scroll compressor of claim 12, wherein the pin portion has
a section in a polygonal or non-circular shape.
14. The scroll compressor of claim 11, wherein the pin portion is
coaxially disposed with respect to the shaft portion, and the
bearing is eccentrically disposed with respect to the pin
portion.
15. A scroll compressor, comprising: a fixed scroll having a fixed
wrap; an orbiting scroll engaged with the fixed wrap to define
compression chambers; a high pressure chamber disposed above the
fixed scroll; a rotation shaft having a shaft portion eccentrically
located with respect to the orbiting scroll, a pin portion located
at an end of the shaft portion and having a diameter smaller than a
diameter of the shaft portion, and a bearing located at an end of
the pin portion; and a drive that drives the rotation shaft,
wherein the pin portion is inserted through the fixed scroll, and
the orbiting scroll is rotatably coupled to the bearing.
16. The scroll compressor of claim 15, further comprising a
discharge pipe that discharges compressed refrigerant from the high
pressure chamber.
17. The scroll compressor of claim 15, further comprising an upper
frame disposed below the orbiting scroll.
18. The scroll compressor of claim 17, wherein the upper frame
divides an inner area of the scroll compressor into the high
pressure chamber and a low pressure chamber.
19. The scroll compressor of claim 15, wherein the pin portion and
the shaft portion are integrally formed with each other.
20. The scroll compressor of claim 15, wherein the pin portion is
inserted into the bearing and fixed thereto.
21. The scroll compressor of claim 15, wherein the pin portion is
coaxially disposed with respect to the shaft portion, and the
bearing is eccentrically disposed with respect to the pin
portion.
22. The scroll compressor of claim 15, wherein an end of the shaft
portion is disposed so as to face a lower surface of the fixed
scroll, and only the pin portion is inserted through the fixed
scroll.
Description
BACKGROUND
[0001] 1. Field
[0002] A scroll compressor is disclosed herein.
[0003] 2. Background
[0004] Scroll compressors are known. However, they suffer from
various disadvantages.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Embodiments will be described in detail with reference to
the following drawings in which like reference numerals refer to
like elements, and wherein:
[0006] FIG. 1 is a schematic sectional view of an inner structure
of a scroll compressor in accordance with an embodiment;
[0007] FIG. 2 is a partial cut view of a compression device of the
scroll compressor of FIG. 1;
[0008] FIG. 3 is a disassembled perspective view of the compression
device of FIG. 2;
[0009] FIG. 4 is an enlarged partial sectional view showing a
portion of the compression device of FIG. 2;
[0010] FIG. 5 is a disassembled perspective view showing a rotation
shaft according to another embodiment;
[0011] FIG. 6 is a partial sectional view showing a rotation shaft
according to another embodiment;
[0012] FIGS. 7A and 7B are planar views showing first and second
compression chambers right after suction and right before discharge
in a scroll compressor including an orbiting wrap and a fixed wrap
having involute shape;
[0013] FIGS. 8A and 8B are planar views showing a shape of an
orbiting wrap in a scroll compressor having an orbiting wrap and a
fixed wrap in another involute shape;
[0014] FIGS. 9A-9E illustrate a process for generating curves for
the scroll compressor of FIG. 1;
[0015] FIG. 10 is a planar view showing final curves generated as
shown in FIGS. 9A-9E;
[0016] FIG. 11 is a planar view showing an orbiting wrap and a
fixed wrap formed using the generated curves of FIG. 10;
[0017] FIG. 12 is an enlarged planar view of a central portion of
the orbiting wrap and fixed wrap of FIG. 11;
[0018] FIG. 13 is a graph showing a relationship between an angle
.alpha. and a compression ratio;
[0019] FIG. 14 is another planar view showing an enlarged central
portion of FIG. 11;
[0020] FIGS. 15A-15B are sectional views of a rotation shaft
coupling portion according to embodiments;
[0021] FIG. 16 is a graph showing change in compression ratio in
response to an average radius of curvature;
[0022] FIG. 17 is a planar view showing a state in which a crank
angle is located at approximately 150.degree.; and
[0023] FIG. 18 is a planar view showing initiation of a discharge
operation in a second compression chamber in the embodiment of FIG.
11.
DETAILED DESCRIPTION
[0024] Hereinafter, description will be made in detail to
embodiments of a scroll compressor with reference to the
accompanying drawings.
[0025] A scroll compressor is a compressor, which includes a fixed
scroll having a fixed wrap and an orbiting scroll having an
orbiting wrap engaged with the fixed wrap. With this configuration
of a scroll compressor, as the orbiting scroll orbits on the fixed
scroll, volumes of compression chambers, which are formed between
the fixed wrap and the orbiting wrap, consecutively change, thereby
sucking and compressing a refrigerant. The scroll compressor allows
suction, compression, and discharge to be consecutively performed,
and it is very favorable, in comparison to other types of
compressors, with respect to vibration and noise generated during
operations.
[0026] The orbiting scroll may include a disk, and the orbiting
wrap may be located at one side of the disk. A boss may be formed
at a rear surface, on which the orbiting wrap is not formed, and
may be connected to a rotation shaft, which allows the orbiting
scroll to perform an orbiting motion. The orbiting wrap may be
formed on almost an entire surface of the plate, thereby reducing a
diameter of the disk for obtaining the same compression ratio. On
the other hand, a point of application, to which a repulsive force
of a refrigerant is applied upon compression, may be
perpendicularly spaced apart from a point of application, to which
a reaction force is applied to attenuate the repulsive force.
Accordingly, the orbiting scroll may be inclined during operation,
thereby generating more vibration and/or noise.
[0027] To obviate such problems, a scroll compressor having a
coupled portion of a rotation shaft and an orbiting scroll located
at or on the same surface as an orbiting wrap has been introduced.
Such structure allows the repulsive force of the refrigerant and
the reaction force to be applied to the same point to solve the
inclination issue of the orbiting scroll. However, when the
rotation shaft extends up to the orbiting wrap, an end portion of
the rotation shaft may penetrate through a disk of the orbiting
scroll. Accordingly, a shaft insertion hole having a diameter as
wide as a diameter of the rotation shaft is needed at or in the
disk of the orbiting scroll. However, this structure causes a
strength of the disk to be reduced. In addition, as the diameter of
the shaft insertion hole formed at or in the disk increases,
leakage of the compressed refrigerant may result.
[0028] FIG. 1 is a schematic sectional view of an inner structure
of a scroll compressor in accordance with an embodiment. FIG. 2 is
a partial cut view of a compression device of the scroll compressor
of FIG. 1, while FIG. 3 is a disassembled perspective view of the
compression device of FIG. 2.
[0029] As shown in FIG. 1, scroll compressor 100 may include a
casing 110, which may be in a cylindrical shape, and an upper shell
112 and a lower shell 114 that cover upper and lower portions of
the casing 110. The upper and lower shells 112 and 114 may be, for
example, welded to the casing 110, so as to define a single
hermetic space together with the casing 110.
[0030] A discharge pipe 116 may be connected to an upper side of
the upper shell 112. The discharge pipe 116 may act as a path
through which a compressed refrigerant may be discharged to outside
of the scroll compressor 100. An oil separator (not shown) that
separates oil mixed with the discharged refrigerant may be
connected to the discharge pipe 116. A suction pipe 118 may be
installed at a side surface of the casing 110. The suction pipe 118
may act as a path through which a refrigerant to be compressed may
be introduced into the scroll compressor 100. Referring to FIG. 1,
the suction pipe 118 may be located at an interface between the
casing 110 and the upper shell 116; however, other positions of the
suction pipe 118 may also be appropriate. In addition, the lower
shell 114 may function as an oil chamber that stores oil, which may
be supplied to make the compressor to allow it to smoothly work or
function.
[0031] A motor 120, which may function as a drive, may be installed
at an approximately central portion within the casing 110. The
motor 120 may include a stator 122, which may be fixed to an inner
surface of the casing 110, and a rotor 124, which may be located
within the stator 122 and rotatable by interaction with the stator
122. A rotation shaft 126 may be disposed in or at a center of the
rotor 124 so as to be rotatable together therewith.
[0032] An oil passage 126a may be formed in or at a center of the
rotation shaft 126 and may extend along a lengthwise direction of
the rotation shaft 126. An oil pump 126b that pumps up oil stored
in the lower shell 114 may be installed at a lower end portion of
the rotation shaft 126. The oil pump 126b may be implemented, for
example, by forming a spiral recess or separately installing an
impeller in the oil passage 126a, or may be a separate pump, which
may be attached or welded thereto.
[0033] A diameter-extended portion 126c, which may be inserted in a
boss formed in a fixed scroll, which will be explained hereinafter,
may be disposed at an upper end portion of the rotation shaft 126.
The diameter-extended portion 126c may have a diameter greater than
a diameter of other potions of the rotation shaft 126. A pin
portion 126d may be formed at an end of the diameter-extended
portion 126c. It is noted that the diameter-extended portion may be
omitted; that is, the entire rotation shaft 126 may have a specific
diameter.
[0034] An eccentric bearing 128 may be inserted onto the pin
portion 126d. Referring to FIG. 3, the eccentric bearing 128 may be
eccentrically inserted onto the pin portion 126d. A coupled portion
between the pin portion 126d and the eccentric bearing 128 may be
in the shape of the letter "D", such that the eccentric bearing 128
cannot be rotated with respect to the pin portion 126d. In
addition, the pin portion 126d may have a polygonal or non-circular
shape. Even in the case of the pin portion 126d having a circular
section, the pin portion 126d may be, for example, welded or
shrink-fitted to the eccentric bearing 128, such that the eccentric
bearing 128 cannot rotate.
[0035] A fixed scroll 130 may be mounted at a boundary portion
between the casing 110 and the upper shell 112. The fixed scroll
130 may have an outer circumferential surface, which may be
shrink-fit between the casing 110 and the upper shell 112.
Alternatively, the fixed scroll 130 may be, for example, welded
with the casing 110 and the upper shell 112.
[0036] A boss 132, in which the rotation shaft 126 may be inserted,
may be formed at a lower surface of the fixed scroll 130. A through
hole, through which the pin portion 126d of the rotation shaft 126
may be inserted, may be formed through an upper surface (see FIG.
1) of the boss 132. Accordingly, the pin portion 126d may protrude
to an upper side of a disk 134 of the fixed scroll 130 through the
through hole.
[0037] A fixed wrap 136, which may be engaged with an orbiting
wrap, which will be explained hereinafter, so as to define
compression chambers, may be formed at an upper surface of the disk
134. A side wall 138 may be located at an outer circumferential
portion of the disk 134. The side wall 138 may define a space that
houses an orbiting scroll 140, which will be explained later, and
may contact an inner circumferential surface of the casing 110. An
orbiting scroll support 138a, on which an outer circumferential
portion of the orbiting scroll 140 may be supported, may be formed
inside at an upper end portion of the side wall 138. A height of
the orbiting scroll support 138a may have the same height as a
height of the fixed wrap 136 or a height slightly higher than the
fixed wrap 136, such that an end of an orbiting wrap 144 may
contact a surface of the disk 134 of the fixed scroll 130.
[0038] The orbiting scroll 140 may be disposed on the fixed scroll
130. The orbiting scroll 140 may include a disk 142, which may have
an approximately circular shape, and the orbiting wrap 144, which
may be engaged with the fixed wrap 136. A rotation shaft coupling
portion 146, which may be in an approximately circular shape, may
be formed in a central portion of the disk 142, such that the
eccentric bearing 128 may be rotatably inserted therein. An outer
circumferential portion of the rotation shaft coupling portion 146
may be connected to the orbiting wrap 144 so as to define
compression chambers together with the fixed wrap 136 during
compression.
[0039] The eccentric bearing 128 may be inserted into the rotation
shaft coupling portion 146, the end portion of the rotation shaft
126 may be inserted through the disk 134 of the fixed scroll 130,
and the orbiting wrap 144, the fixed wrap 136, and the eccentric
bearing 128 may overlap together in a lateral direction of the
compressor. Upon compression, a repulsive force of a refrigerant
may be applied to the fixed wrap 136 and the orbiting wrap 144,
while a compression force as a reaction force against the repulsive
force may be applied between the rotation shaft coupling portion
146 and the eccentric bearing 128. As such, when the shaft is
partially inserted through the disk and overlaps with the wraps,
the repulsive force of the refrigerant and the compression force
may be applied at or to the same side surface of the disk, thereby
being attenuated by each other. Consequently, the orbiting scroll
140 may be prevented from being inclined due to the compression
force and the repulsive force. As alternate example, an eccentric
bushing may be used instead of the eccentric bearing. In this
example, an inner surface of the rotation shaft coupling portion
146, in which the eccentric bushing may be inserted, may be
configured to serve as a bearing. Other examples of installing a
separate bearing between the eccentric bearing and the rotation
shaft coupling portion may also be appropriate.
[0040] Further, a diameter of the pin portion 126d, which
penetrates the disk 134 of the fixed scroll 130, may be smaller
than a diameter-extended part (shaft portion) 126c of the rotation
shaft 126. Accordingly, a diameter of the shaft insertion hole
formed at or in the fixed scroll 130 may be reduced by that amount,
which may prevent a strength of the fixed scroll 130 from being
reduced due to the shaft insertion hole, and reduce or prevent any
leaking of compressed refrigerant between the pin portion 126d and
the shaft insertion hole.
[0041] In particular, as shown in FIG. 4, the disk 134 of the fixed
scroll 130 may be secured between an end of the pin portion 126d
and an end of the eccentric bearing 128, so refrigerant may flow
along a path indicated with an arrow to be leaked out of the
compression chamber. Hence, the leakage path can be extended, in
comparison to the related art scroll compressor in which the shaft
portion penetrates directly through the disk, and thereby the
leakage prevention effect may be improved.
[0042] The eccentric bearing 128 may also function as a bearing for
smooth rotation of the orbiting scroll 140. In addition, a separate
bearing may be installed at an outer circumferential portion of the
eccentric bearing 128.
[0043] Although not shown, a discharge hole, through which
compressed refrigerant may flow into the casing 110, may be formed
through the disk 142. The position of the discharge hole may be set
by considering, for example, a required discharge pressure.
[0044] An Oldham ring 150 that prevents rotation of the orbiting
scroll 140 may be installed on the orbiting scroll 140. The Oldham
ring 150 may include a ring portion 152, which may have an
approximately circular shape, and may be inserted onto a rear
surface of the disk 142 of the orbiting scroll 140, and a pair of
first keys 154 and a pair of second keys 156 that protrude from one
side surface of the ring part 152. The first pair of keys 154 may
protrude longer than a thickness of an outer circumferential
portion of the disk 142 of the orbiting scroll 140, and may be
inserted into first key recesses 137, which may be recessed into an
upper end of the side wall 138 of the fixed scroll 130 and the
orbiting scroll support 138a. The second pair of keys 156 may be
inserted into second key recesses 147, which may be formed at or in
the outer circumferential portion of the disk 142 of the orbiting
scroll 140.
[0045] Each of the first key recesses 137 may have a first or
vertically extending portion 137a that extends upwardly and a
second or horizontally extending portion 137b that extends in a
right-left direction. During an orbiting motion of the orbiting
scroll 140, a lower end portion of each of the pair of first keys
154 may remain inserted in the horizontally extending portion 137b
of the corresponding first key recess 137, while an outer end
portion of the first key 154 may be separated in a radial direction
from the vertically extending portion 137a of the first key recess
137. That is, the first key recesses 137 and the fixed scroll 130
may be coupled to each other in a perpendicular direction, which
may allow reduction of a diameter of the fixed scroll 130.
[0046] In more detail, a clearance (air gap) as wide as an orbiting
radius may be provided between the disk 142 of the orbiting scroll
140 and an inner wall of the fixed scroll 130. If the Oldham ring
150 is coupled to the fixed scroll 130 in a radial direction, the
key recesses 137 formed at or in the fixed scroll 130 may be longer
than at least the orbiting radius in order to prevent the Oldham
ring 150 from being separated from the key recesses 137 during the
orbiting motion. However, this structure may cause an increase in
size of the fixed scroll. On the other hand, as shown in the
exemplary embodiment, if the key recesses 137 extend down to a
lower side of a space between the disk 142 of the orbiting scroll
140 and the orbiting wrap 144, a sufficient length of the key
recess 137 may be ensured even without increasing the size of the
fixed scroll 130.
[0047] In addition, in the exemplary embodiment, all of the keys of
the Oldham ring 150 may be formed at or on the one side surface of
the ring portion 152. This structure may thus reduce a
perpendicular height of a compression device in comparison to
forming keys at both side surfaces.
[0048] A lower frame 160 that rotatably supports a lower side of
the rotation shaft 126 may be installed at a lower side of the
casing 110, and an upper frame 170 that supports the orbiting
scroll 140 and the Oldham ring 150 may be installed on the orbiting
scroll 140. A hole may be provided at a central portion of the
upper frame 170. The hole may communicate with the discharge hole
of the orbiting scroll 140 to allow compressed refrigerant to be
discharged toward the upper shell 112. Further, scrolls, such as
for example, one or more elastic o-rings, may be provided between
the orbiting scroll and the upper frame 170.
[0049] The exemplary embodiment shows that the pin portion 126d and
the shaft portion may be integrally formed. However, embodiments
are not limited to such structure. As an alternative example, the
eccentric bearing 128 and the pin portion 126d may be integrally
formed and the pin portion 126d may be inserted into the shaft
portion.
[0050] FIG. 5 is a disassembled perspective view showing a
rotational shaft according to another embodiment. As shown in FIG.
5, the eccentric bearing 128 and the pin portion 126d may be
integrally formed to have a shape similar to the letter "T", and a
pin fixing groove 126e may be formed at an end of the shaft portion
126c, such that the pin portion 126d may be inserted therein.
Sections of the pin portion 126d and the pin fixing groove 126e may
have a shape similar to the letter "D", so as to prevent the pin
portion 126d from being rotated within the pin fixing groove 126e.
Also, the pin portion 126d shown in FIG. 1 may penetrate the disk
134 of the fixed scroll 130; however, embodiments are not limited
to this structure.
[0051] FIG. 6 is a partial sectional view showing a rotation shaft
according to another embodiment. In the embodiment of FIG. 6, like
reference numerals have been used to indicate like elements, and
repetitive disclosure has bee omitted. Further, the pin portion
126d of the scroll compressor 200 may penetrate the disk 142 of the
orbiting scroll 140. Referring to FIG. 6, the fixed scroll 130
including the disk 134 and the fixed wrap 136 may be fixed onto an
inner wall of the casing 110. The fixed wrap 136 of the fixed
scroll 130 may be located at a lower portion of the disk 134,
unlike the structure in FIG. 1.
[0052] The orbiting scroll 140 may be disposed beneath the fixed
scroll 130. The upper frame 70 may be disposed below the orbiting
scroll 142, as shown in FIG. 6. The orbiting wrap 144, which may be
engaged with the fixed wrap 136 to define a compression chamber,
may be disposed at an upper portion of the disk 142 of the orbiting
scroll 140. The rotation shaft coupling portion 146, to which the
rotation shaft may be coupled, may be formed at a central portion
of the orbiting wrap 140. A boss 145, in which the shaft portion
126c of the rotation shaft may be rotatably inserted, may be formed
at a lower portion of the rotation shaft coupling portion 146. A
shaft insertion hole, through which the pin portion 126d of the
rotation shaft 126 may be inserted, may be formed through the disk
142 located between the boss 145 and the rotation shaft coupling
portion 146.
[0053] Therefore, the exemplary embodiment of FIG. 6 is different
from the exemplary embodiment of FIG. 1, in that the shaft portion
126c, the pin portion 126d, and the eccentric bearing 128 of the
rotation shaft 126 may all be coupled onto the orbiting scroll 140
without being coupled to the fixed scroll 130.
[0054] Hereinafter, description will be given of an orbiting wrap
and a fixed wrap, each having an involute form according to
embodiments.
[0055] FIGS. 7A and 7B are planar views showing a compression
chamber right after a suction operation and a compression chamber
right before a discharge operation in a scroll compressor having an
orbiting wrap and a fixed wrap formed as an involute curve and
having a shaft partially inserted through a disk. In particular,
FIG. 7A shows the change of a first compression chamber defined
between an inner side surface of the fixed wrap and an outer side
surface of the orbiting wrap, and FIG. 7B shows the change of a
second compression chamber defined between an inner side surface of
the orbiting wrap and an outer side surface of the fixed wrap.
[0056] In such a scroll compressor, a compression chamber is
defined between two contact points generated by contact between the
fixed wrap and the orbiting wrap. In a case in which the fixed wrap
and the orbiting wrap have an involute curve shape, as shown in
FIGS. 7A and 7B, the two contact points defining one compression
chamber are on the same line. In other words, the compression
chamber may extend 360.degree. about a center of the rotation
shaft.
[0057] Regarding a volume change of the first compression chamber,
shown in FIG. 7A, a volume of the first compression chamber is
gradually reduced as it moves toward a central portion in response
to the orbiting motion of the orbiting scroll. Thus, when arriving
at an outer circumferential portion of a rotation shaft coupling
portion located at a center of the orbiting scroll, the first
compression chamber has a minimum volume value. For the fixed wrap
and the orbiting wrap having the involute curve shape, the volume
reduction rate linearly decreases as an orbiting angle
(hereinafter, referred to as a `crank angle`) of the rotation shaft
increases. Hence, to acquire a high compression ratio, the first
compression chamber should be moved as close to the center as
possible. However, when the rotation shaft is present at the
central portion, the compression chamber may only move up to the
outer circumferential portion of the rotation shaft. Accordingly,
the compression ratio is lowered. A compression ratio of about 2.13
is exhibited in FIG. 7A.
[0058] Meanwhile, the second compression chamber, shown in FIG. 7B,
has a compression ratio of about 1.46, which is lower than that of
the first compression chamber. However, regarding the second
compression chamber, if the shape of the orbiting scroll is changed
such that a connected portion between a rotation shaft coupling
portion and the orbiting wrap is formed in an arcuate shape, a
compression path of the second compression chamber before a
discharge operation may be extended, thereby increasing the
compression ratio up to about 3.0. In this case, the second
compression chamber may extend less about 360.degree. about the
center of rotation of the rotation shaft right before the discharge
operation. However, this method may not be applied to the first
compression chamber.
[0059] Therefore, when the fixed wrap and the orbiting wrap have
the involute curve shape, a compression ratio of the second
compression chamber may be as high as possible, but a compression
ratio of the first compression chamber may not. Also, when the two
compression chambers have a significant difference between their
respective compression ratios, it may adversely affect the
operation of the compressor and may lower the overall compression
ratio.
[0060] To solve this problem, the exemplary embodiment shown in
FIGS. 9A-9E includes a fixed wrap and an orbiting wrap having a
different curve (shape) from an involute curve. That is, FIGS. 9A
to 9E show a process of determining shapes of the fixed wrap and
the orbiting wrap according to the exemplary embodiment. In FIGS.
9A-9E, a solid line indicates a generated curve for the first
compression chamber and a dotted line indicates a generated curve
for the second compression chamber.
[0061] The generated curve refers to a track drawn by a particular
shape during movement. The solid line indicates a track drawn by
the first compression chamber during suction and discharge
operations, and the dotted line indicates the track of the second
compression chamber. Hence, if the generated curve is extended
outward from its two opposite sides along the orbiting radius of
the orbiting scroll based upon the solid line, it represents shapes
of an inner side surface of the fixed wrap and an outer side
surface of the orbiting wrap. If the generated curve is extended
outward to its two opposite sides based upon the dotted line, it
represents shapes of an outer side surface of the fixed wrap and an
inner side surface of the orbiting wrap.
[0062] FIG. 9A shows a generated curve corresponding to a wrap
shape shown in FIG. 8A. In FIG. 9A, the bold line corresponds to
the first compression chamber right before a discharge operation.
As shown, a start point and an end point are present on the same
line. In this case, it may be difficult to achieve a sufficient
compression ratio. Thus, as shown in FIG. 9B, an end portion of the
bold line, the outer end portion, may be transferred or shifted in
a clockwise direction along the generated curve, and the other end
portion, the inner end portion, may be transferred or shifted to a
point to contact the rotation shaft coupling portion. That is, a
portion of the generated curve, adjacent to the rotation shaft
coupling portion, may be curved so as to have a smaller radius of
curvature.
[0063] As described above, the compression chamber may be defined
by two contact points at which the orbiting wrap and the fixed wrap
contact each other. The two ends of the bold line in FIG. 9A
correspond to the two contact points. Normal vectors at the
respective contact points are in parallel to each other according
to the operating algorithm of the scroll compressor. Also, the
normal vectors are in parallel to a line connecting a center of the
rotation shaft and a center of the eccentric bearing. For a fixed
wrap and an orbiting wrap having an involute curve shape, the two
normal vectors are in parallel to each other and also present on
the same line, as shown in FIG. 9A.
[0064] That is, if it is assumed that the center of the rotation
shaft coupling portion 146 is O and the two contact points are P1
and P2, P2 is located on a line connecting O and P1. If it is
assumed that a larger angle of the two angles formed by lines OP1
and OP2 is .alpha., .alpha. is 360.degree.. In addition, if it is
assumed that a distance between the normal vectors at P1 and P2 is
l, l is 0.
[0065] When P1 and P2 are transferred more internally along the
generated curves, the compression ratio of the first compression
chamber may be improved. To this end, when P2 is transferred or
shifted toward rotation shaft coupling portion 146, namely, the
generated curve for the first compression chamber is transferred or
shifted toward thoiohaft coupling portion 146, P1, which has a
normal vector in prallel to the normal vector at P2, then rotates
in a clockwise direction from the position shown in FIG. 9A to the
position shown in FIG. 9B, thereby being located at the rotated
point. As described above, the first compression chamber is reduced
in volume as it is transferred or shifted more internally along the
generated curve. Hence, the first compression chamber shown in FIG.
9B may be transferred or shifted more internally as compared to
FIG. 9A, and further compressed a corresponding amount, thereby
obtaining an increased compression ratio.
[0066] Referring to FIG. 9B, the point P1 may be considered
excessively close to the rotation shaft coupling portion 146.
Accordingly, the rotation shaft coupling portion 146 may have to
become thinner to accommodate this. Hence, the point P1 is
transferred back so as to modify the generated curve, as shown in
FIG. 9C. In FIG. 9C, the generated curves of the first and second
compression chambers may be considered to be excessively close to
each other, which corresponds to an excessively thin wrap thickness
or renders it physically too difficult to form the wrap(s). Thus,
as shown in FIG. 9D, the generated curve of the second compression
chamber may be modified such that the two generated curves maintain
a predetermined interval therebetween.
[0067] Further, the generated curve of the second compression
chamber may be modified, as shown in FIG. 9E, such that an arcuate
portion C located at the end of the generated curve of the second
compression chamber may contact the generated curve of the first
compression chamber. The generated curves may be modified to
continuously maintain a predetermined interval therebetween. When a
radius of the arcuate portion C of the generated curve of the
second compression chamber is increased to ensure a wrap rigidity
at the end of the fixed wrap, generated curves having the shape
shown in FIG. 10 may be acquired.
[0068] FIG. 11 is a planar view showing an orbiting wrap and a
fixed wrap obtained based on the generated curves of FIG. 10, and
FIG. 12 is an enlarged planar view of the central portion of FIG.
11. For reference, FIG. 11 shows a position of the orbiting wrap at
a time point of initiating the discharge operation in the first
compression chamber. The point P1 in FIG. 11 indicates a point of
two contact points defining a compression chamber, at a moment when
initiating discharging in the first compressor chamber. Line S is a
virtual line that indicates a position of the rotation shaft and
Circle C is a track drawn by the line S. Hereinafter, the crank
angle is set to 0.degree. when the line S is present in a state
shown in FIG. 11, namely, when initiating discharging, set to a
negative (-) value when rotated counterclockwise, and set to a
positive (+) value when rotated clockwise.
[0069] Referring to FIGS. 11 and 12, an angle .alpha. defined by
the two lines which respectively connect the two contact points P1
and P2 to the center P of the rotation shaft coupling portion may
be smaller than about 360.degree., and a distance l between the
normal vectors at each of the contact points P1 and P2 may be
greater than about 0. Accordingly, the first compression chamber
right before a discharge operation may have a smaller volume than
that defined by the fixed wrap and the orbiting wrap having the
involute curve shape, which results in an increase in the
compression ratio. In addition, the orbiting wrap and the fixed
wrap shown in FIG. 11 have a shape in which a plurality of arcs
having different diameters and origins are connected and the
outermost curve may have an approximately oval shape with a major
axis and a minor axis.
[0070] In the exemplary embodiment, the angle .alpha. may be in the
range of, for example, approximately 270.degree. to 345.degree..
FIG. 13 is a graph showing the angle .alpha. and the compression
ratio. From the perspective of improvement of the compression
ratio, it may be advantageous to set the angle .alpha. to have a
low value. However, if the angle .alpha. is smaller than
approximately 270.degree., it may cause mechanical fabrication,
make production and assembly difficult, and increase a price of the
compressor. If the angle .alpha. exceeds approximately 345.degree.,
the compression ratio may be lowered below 2.1, thereby failing to
provide a sufficient compression ratio.
[0071] In addition, a protruding portion 165 may protrude from an
inner end of the fixed wrap toward the rotation shaft coupling
portion 146. A contact portion 162 may be formed at the end of the
protruding portion 165. That is, the inner end of the fixed wrap
130 may be thicker than other portions. Accordingly, a wrap
rigidity of the inner end of the fixed wrap, to which the strongest
compression force may be applied, may be improved, resulting in
enhancing durability.
[0072] The thickness of the fixed wrap may be gradually decreased,
starting from the inner contact point P1 of the two contact points
defining the first compression chamber upon initiating the
discharge operation, as shown in FIG. 12. More particularly, a
first decrease portion 164 may be formed adjacent to the contact
point P1 and a second decrease portion 166 may extend from the
first decrease portion 164. A thickness reduction rate of the first
decrease portion 164 may be higher than that of the second decrease
portion 166. After the second decrease portion 166, the fixed wrap
may be increased in thickness within a predetermined interval.
[0073] If it is assumed that a distance between an inner side
surface of the fixed wrap and a center O of the rotation shaft is
DF, then DF may be increased and then decreased as it progresses
away from P1 in a counterclockwise direction (based on FIG. 12),
and such interval is shown in FIG. 17. FIG. 17 is a planar view
showing the position of the orbiting wrap 150.degree. before
initiating the discharge operation, namely, when the crank angle is
about 150.degree.. If the rotation shaft rotates about 150.degree.
from the state of FIG. 17, it reaches the state shown in FIG. 11.
Referring to FIG. 14, an inner contact point P5 of two contact
points defining the first compression chamber is located above the
rotation shaft coupling portion 146, and the DF is increased and
then decreased at the interval from P3 of FIGS. 14 to P4 of FIG.
17.
[0074] The rotation shaft coupling portion 146 may be provided with
a recess portion 180 to be engaged with the protruding portion 165.
One side wall of the recess portion 180 may contact the contact
portion 162 of the protruding portion 165 to define one contact
point of the first compression chamber. If it is assumed that a
distance between the center of the rotation shaft coupling portion
146 and an outer circumferential portion of the rotation shaft
coupling portion 146 is Do, then Do may be increased and then
decreased at the interval between P1 of FIGS. 9 and P4 of FIG. 17.
Similarly, the thickness of the rotation shaft coupling portion 146
may also be increased and then decreased at the interval between P1
of FIGS. 11 and P4 of FIG. 17.
[0075] The one side wall of the recess portion 180 may include a
first increase portion 182 at which a thickness is relatively
significantly increased, and a second increase portion 184
extending from the first increase portion 182 and having a
thickness increased at a relatively low rate. These correspond to
the first decrease portion 164 and the second decrease portion 166
of the fixed wrap. The first increase portion 182, the first
decrease portion 164, the second increase portion 184, and the
second decrease portion 166 may be obtained by turning the
generated curve toward the rotation shaft coupling portion 146 at
the step of FIG. 9B. Accordingly, the inner contact point P1
defining the first compression chamber may be located at the first
and second increase portions, and also the length of the first
compression chamber right before the discharge operation may be
shortened so as to enhance the compression ratio.
[0076] Another side wall of the recess portion 180 may have an
arcuate shape. A diameter of the arc may be decided by the wrap
thickness of the end of the fixed wrap and the orbiting radius of
the orbiting wrap. When the thickness of the end of the fixed wrap
increases, the diameter of the arc may increase. Accordingly, the
thickness of the orbiting wrap near the arc may increase to provide
durability and the compression path may also extend so as to
increase the compression ratio of the second compression
chamber.
[0077] The central portion of the recess portion 180 may form a
part of the second compression chamber. FIG. 18 is a planar view
showing the position of the orbiting wrap when initiating the
discharge operation in the second compression chamber. Referring to
FIG. 18, the second compression chamber is defined between two
contact points P6 and P7 and contacts an arcuate side wall of the
recess portion 180. When the rotation shaft rotates further, one
end of the second compression chamber may pass through the center
of the recess portion 180.
[0078] FIG. 14 is another planar view showing a state corresponding
to the state shown in FIG. 12. It may be noticed, referring to FIG.
14, that a tangent line T drawn at the point P3 (which corresponds
to the point P1 in FIG. 11) passes through the inside of the
rotation shaft coupling portion 146. This results from the
generated curve being curved inwardly during the process of FIG.
9B. Consequently, a distance between the tangent line T and a
center of the rotation shaft coupling portion 146 may be smaller
than a diameter RH within the rotation shaft coupling portion.
[0079] The inner diameter RH may be defined as an inner diameter of
the rotation shaft coupling portion 146 when an inner
circumferential surface of the rotation shaft coupling portion 146
or an outer circumferential surface of the eccentric bearing 128 is
lubricated, as shown in FIG. 15A, without a separate bearing,
whereas being defined as an outer diameter of the bearing when a
separate bearing is additionally employed within the rotation shaft
coupling portion 146, as shown in FIG. 15B.
[0080] In FIG. 14, the point P5 denotes an inner contact point when
the crank angle is about 90.degree., and as shown, a radius of
curvature of an outer circumference of the rotation shaft coupling
portion may have various values depending on each position between
the points P3 and P5. Here, the average radius of curvature Rm
defined by the following equation may influence on the compression
ratio of the first compression chamber.
R m = 1 90 .intg. 0 90 R .theta. .theta. ##EQU00001##
where R.theta. is a radius of curvature of the orbiting wrap at the
inner contact point of the first compression chamber when the crank
angle is .theta..
[0081] FIG. 16 is a graph showing a relationship between an average
radius of curvature and compression ratio. In general, a rotary
compressor may preferably have a compression ratio more than about
2.3 when being used for both cooling and heating, and more than
about 2.1 when being used for cooling. Referring to FIG. 16, when
the average radius of curvature is less than about 10.5, the
compression ratio may be more than about 2.1. Therefore, if Rm is
set to be less than 10.5 mm, the compression ratio may be more than
about 2.1. Here, the Rm may be optionally set to be suitable for
the use of the scroll compressor. In the exemplary embodiment, the
RH may have a value of approximately about 15 mm. Therefore, the Rm
may be set to be smaller than RH/1.4.
[0082] Meanwhile, the point P5 may not always be limited when the
crank angle is about 90.degree.. In view of the operating algorithm
of the scroll compressor, a design variable with respect to a
radius of curvature after 90.degree. is low. Accordingly, in order
to improve a compression ratio, it is advantageous to change a
shape between about 0.degree. and 90.degree., in which the design
variable is relatively high.
[0083] Embodiments disclosed herein provide a scroll compressor
capable of minimizing a strength reduction of a disk of an orbiting
scroll, even if the orbiting wrap and a rotation shaft are coupled
to each other on a same side surface.
[0084] Embodiments disclosed herein provide a scroll compressor
that may include a fixed scroll having a fixed wrap, an orbiting
scroll engaged with the fixed wrap to define a compression chamber,
a rotation shaft having a shaft portion eccentrically located from
the orbiting scroll, a pin portion located at an end of the shaft
portion and having a diameter smaller than that of the shaft
portion, and a bush located at an end of the pin portion, and a
drive to drive the rotation shaft, wherein the pin portion is
inserted through one of the fixed scroll or the orbiting scroll,
and the orbiting scroll is rotatably coupled to the bush.
[0085] A portion of the rotation shaft that penetrates the disk of
the orbiting scroll may be formed to have a diameter smaller than
other portions of the rotation shaft so that the size of the shaft
insertion hole of the disk may be smaller in diameter than the
shaft portion, which results in reduction in a lowered disk
strength and a minimization of leakage of a refrigerant.
Especially, the disk may be secured between the shaft portion and
the bush, so that a refrigerant leakage path may be remarkably
extended as compared to the related art, thereby minimizing leakage
of refrigerant.
[0086] The pin portion and the shaft portion may be formed
integrally with each other. With this structure, the pin portion
may be inserted into the bush and fixed thereto. To this end, the
bush may be fixed into the pin portion, for example, by welding or
shrink-fitting. Alternatively, the pin portion may be formed to
have a polygonal or non-circular section so that the bush inserted
into the pin portion cannot rotate with respect to the pin portion.
The pin portion may be coaxially disposed with respect to the shaft
portion, and the bush may be eccentrically disposed with respect to
the pin portion.
[0087] The pin portion and the bush may be integrally formed with
each other. The pin portion may be inserted into the shaft portion
and fixed thereto so as to be rotatable together with the shaft
portion. The pin portion may have a section in a polygonal or
non-circular shape. In addition, the pin portion may be coaxially
disposed with respect to the shaft portion, and the bush may be
eccentrically disposed with respect to the pin portion.
[0088] The portion of the rotation shaft penetrating the disk of
the orbiting scroll may be formed to have a diameter smaller than
other portions of the rotation shaft, thus a size of the shaft
insertion hole of the disk may be smaller than the diameter of the
shaft portion. Accordingly, the lowering of the strength of the
disk may be reduced and leakage of the refrigerant may be
minimized. Especially, the disk is secured between the shaft
portion and the bush, so a refrigerant leakage path may be extended
in comparison to the related art, thereby minimizing the fear for
the refrigerant leakage.
[0089] Any reference in this specification to "one embodiment," "an
embodiment," "example embodiment," etc., means that a particular
feature, structure, or characteristic described in connection with
the embodiment is included in at least one embodiment of the
invention. The appearances of such phrases in various places in the
specification are not necessarily all referring to the same
embodiment. Further, when a particular feature, structure, or
characteristic is described in connection with any embodiment, it
is submitted that it is within the purview of one skilled in the
art to effect such feature, structure, or characteristic in
connection with other ones of the embodiments.
[0090] Although embodiments have been described with reference to a
number of illustrative embodiments thereof, it should be understood
that numerous other modifications and embodiments can be devised by
those skilled in the art that will fall within the spirit and scope
of the principles of this disclosure. More particularly, various
variations and modifications are possible in the component parts
and/or arrangements of the subject combination arrangement within
the scope of the disclosure, the drawings and the appended claims.
In addition to variations and modifications in the component parts
and/or arrangements, alternative uses will also be apparent to
those skilled in the art.
* * * * *